Altered health maintenance related to acid-base imbalances
OUTCOMES. Knowledge: Diet; Disease process; Health behaviors; Medication: Treatment regime; Nutritional status; Electrolyte and acid-base balance
INTERVENTIONS. Acid-base management; Acid-base monitoring; Health education; Risk identification; Teaching: Disease process; Referral; Medication management; Nutritional management
GENERAL. The highest priority for all patients with acid-base imbalances is to maintain the adequacy of airway, breathing, and circulation. An important focus for collaborative treatment is to deliver oxygen, remove carbon dioxide, and monitor gas exchange. Treatment is focused on correcting the cause and restoring fluids and electrolytes to a normal range. Provide constant cardiac monitoring for patients with hypokalemia, hypocalcemia, and hypomagnesemia. Consult with a dietitian to provide foods that can help restore electrolyte balance and increase oral intake. If a patient demonstrates impaired physical mobility, consult a physical therapist to evaluate the patient's abilities and to recommend needed strengthening exercises and assist devices.
Metabolic Acidosis. Sodium bicarbonate may be administered to treat normal anion gap metabolic acidosis but is controversial in treating increased anion gap metabolic acidosis. Research has shown that administering sodium bicarbonate may inhibit hemoglobin release of oxygen to the tissues, thus increasing the acidosis. Sodium bicarbonate is recommended if the pH is greatly reduced (<7.2). Sodium bicarbonate may be administered by intravenous drip or by intravenous push. Overmedication of sodium bicarbonate may cause metabolic alkalosis, fluid volume overload, hypokalemia, and worsened acidosis. Potassium-sparing diuretics, amphotericin B, and large quantities of isotonic saline solutions should not be administered to patients with suspected renal failure. These drugs may contribute to the development of metabolic acidosis.
Metabolic Alkalosis. Pharmacologic therapy may include IV saline solutions, potassium supplements, histamine antagonists, and carbonic anhydrase inhibitors. IV saline solutions (0.9% or 0.45%) may be used to replace lost volume and chloride ions. Causes of metabolic alkalosis that respond favorably to saline therapy include vomiting, NG suctioning, post chronic hypercapnia, and diuretic therapy. The causes of metabolic alkalosis that do not respond favorably to the administration of saline include hypokalemia and mineralocorticoid excess. Potassium chloride is used to treat hypokalemia in a patient with metabolic alkalosis. Dietary supplements of potassium are not effective unless chloride levels are stabilized.
Histamine H2 receptor antagonists, particularly cimetidine and ranitidine, reduce the production of hydrochloric acid in the stomach and may prevent the occurrence of metabolic alkalosis in patients with NG suctioning and vomiting.
The carbonic anhydrase inhibitor acetazolamide (Diamox) is useful for correcting metabolic alkalosis in patients with congestive heart failure who cannot tolerate fluid volume administration. Acetazolamide promotes the renal excretion of bicarbonate. Severe metabolic alkalosis may require the administration of weak acid solutions. Because acetazolamide promotes the excretion of potassium, it is not given until serum potassium levels are evaluated as safe.
Potassium-sparing diuretics, such as spironolactone, may be used if diuretics are needed. Anticonvulsants are usually not needed because the risk for seizures decreases as fluid and electrolyte imbalances are corrected.
Respiratory Acidosis. Although oxygen therapy is required to treat the hypoxemia that accompanies respiratory acidosis, a fraction of inspired air (FiO2) of less than 0.40 is desirable. Oxygen concentrations greater than 0.80 are toxic to the lung over a 5 to 6-day time period. Caution: The use of oxygen for patients with COPD and hypercapnia may remove the stimulus for respiration and result in respiratory depression. If the PaCO2 is greater than 60 mm Hg or the PaO2 is less than 50 mm Hg with high levels of supplemental oxygen, intubation and mechanical ventilation are required. Pharmacologic therapy for respiratory acidosis depends on the cause and severity of acidosis. The administration of sodium bicarbonate is controversial for a pH greater than 7.0. If the pH is below 7.0, sodium bicarbonate administration is recommended. Bronchodilators may be used to decrease bronchospasms. Antibiotics are prescribed for respiratory infections, but sedatives that depress respirations are limited.
Respiratory Alkalosis. Because the most common cause of respiratory alkalosis is anxiety, reassurance and sedation may be all that are needed. Pharmacologic therapy most likely includes the administration of anti-anxiety medications and potassium supplements. Benzodiazepines, commonly used to control acute anxiety attacks, are administered intramuscularly or intravenously. If the anxiety is more severe and the respiratory alkalosis is pronounced, rebreathing small amounts of exhaled air with a paper bag or a rebreather mask helps increase arterial PaCO2 levels and decrease arterial pH. If the cause of the hyperventilation is hypoxemia, oxygen therapy is needed. Overventilation by mechanical ventilation can be easily remedied by decreasing the respiratory rate or tidal volume. If ventilator changes do not decrease the pH, dead space can be added to the ventilator tubing. Dead space provides a smaller volume of air so that less CO2 can be expired.
For patients who are acutely ill, the priority is to maintain a patent airway, which can be managed through positioning or the use of an oral airway or endotracheal tube. Position patient in a semi-Fowler position to allow for optimal chest wall expansion, patient comfort, and adequate gas exchange. Aggressive pulmonary hygiene techniques are used to mobilize secretions and increase alveolar ventilation. These measures should include turning, coughing, and deep breathing every 2 hours; postural drainage and percussion every 4 hours; and sitting up in a chair twice per day.
Orient a confused patient to person, time, and place. Use clocks, calendars, family photos, and scheduled rest periods to help maintain orientation. Assist the patient in using hearing aids and glasses to ensure an accurate interpretation of surroundings. Consider using restraints according to hospital policy if the risk for injury is high. Remove the restraints every 2 hours to allow for range-of-motion exercises. Incorporate the patient's normal sleep routines into the care plan. Schedule collaborative activities to allow at least two 1-hour rest periods during the day and one 4-hour rest period at night.
Provide assistance as needed in feeding, bathing, toileting, and dressing. Provide frequent mouth care (every 2 hours) to ensure patient comfort. If the patient is able to swallow, offer sips of water or ice chips every hour. Avoid lemon glycerine swabs, which may cause dryness. The patient is not discharged until the cause of the acid-base alteration has been resolved; in many patients, however, underlying organ diseases may not be resolved.
• Physical findings: Flushed, dry, warm skin; mental status (presence of disorientation or confusion); respiratory rate and pattern, breath sounds; cardiac rhythm and rate, blood pressure, quality of pulses, urine output; level of consciousness, orientation, ability to concentrate, motor strength, and seizure activity (if seizures are present, the following information should be charted: time the seizure began, parts of the body involved in the seizure, progression of the seizure, type of body movements, pupil size and reaction, eye movements, vital signs during seizure and postictal state)
• Response to therapy: Medications, activity, interventions
• Laboratory values: Arterial blood gases (ABGs) and serum potassium, calcium, sodium, chloride, and magnesium
The patients at highest risk for a recurrence of acid-base imbalances are those who consume large quantities of thiazide diuretics, antacids, and licorice, as well as those who have chronic renal, pulmonary, cardiac, and neurological disorders and IDDM. Make sure these patients understand the importance of maintaining the prescribed treatment regimen. Teach patients on diuretic therapy the signs and symptoms of the associated fluid and electrolyte disturbances of hypovolemia and hypokalemia. Teach patients the action, dose, and side effects of all medications. Teach the patient with mild-to-moderate anxiety progressive muscle relaxation, therapeutic breathing, and visualization techniques to control anxiety.
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